Process for producing artificial silk



April 13, 1937. G. I. THURMOND 2,076,801

PROCESS FOR PRODUCING ARTIFICIAL SILK Filed Nov. 24, 19s:

NVENTOR BYZ I 'ATTERNE? Patented Apr. 13, 1937 UNITED STATES PATENT OFFICE Gilbert I. Thurmond, Asheville, N. (3., assignor to American Enka Corporation, Enka, N. 0., a corporation of Delaware Application November 24, 1933, Serial No. 699,622?) 12 Claims.

This invention relates to artificial silk filaments and to the manufacture of the same, and more particularly to the product and the production of viscose threads and the like by the so-called stretch spinning process.

The process broadly includes means for extruding the viscose solution through very fine openings into a coagulating bath from which it is carried off by suitable thread guides or rollers to the bobbin or pot, as the case may be. During its path of travel the thread is subjected to a stretching action.

Past practices involving the stretch-spinning method in the production of artificial silk filaments have resulted in the encounter of numerous difiiculties, one of which, being that after the thread has been wound on the bobbin and treated in the ordinary manner and subsequently dyed, the rate of dyeing or the rate of the absorpgo tlon of the dye is higher on the outside layers of the yarn. Earlier results were also disadvantageous in that a diflerence in the color intensity of the dyed yarn occurred throughout the yarn package.

The reason for the above referred to differences in the dyeing of the thread is due to the fact that the inner layers of thread are wound on a substantially rigid form and cannot therefore contract to an appreciable extent, while the outer 30 layers are able to contract to a larger degree.

It is an object of the present invention to overcome the dimculties heretofore encountered by the production of yarn having varying dye absorption properties, and to produce artificial silk ac threads by the stretch-spinning process which will have substantially uniform dyeing characteristics.

A further object of this invention is to provide a process for stretching the yarn in a constantly increasing manner from the inside to the outside 40 of the bobbin upon which it is wound.

It is further contemplated to employ a suitable apparatus in which this process can be carried. out.

Other objects will appear from the following description when considered in connection with the accompanying drawing wherein,

Fig. I is a diagrammatic side view of one form of the apparatus for practicing the present method.

Fig. II is, a top view of the mechanism shown in Fig.1. I

Fig. III is a diagrar'nmatic side view of a modifled form of the'apparatus for practicing this 55 invention, and

Fig. IV is a top view of the modified form of the apparatus shown in Fig. III.

Referring to Figures I and II, I designates the spinnerette from which the yarn 2 is extruded. The yarn 2 is led around the godet wheel 3 one 5 or more times and thence'carried to a second godet wheel 4. After the yarn has been wound around the second godet wheel l one or more times it may, if desired, be led around a roller 5. Finally the yarn is wound upon a bobbin 6. 10

The godet wheels 3 and 4 are positively driven by any suitable means (not shown). The peripheral speeds of these two wheels are maintained different so that a constant stretching action is given to the yarn between the two wheels. Dur- 15 ing the period of winding the yarn on the bobbin, the peripheral speeds of the two godet wheels are maintained constantly difierent but at the same time the peripheral speeds of the two godet wheels are gradually decreased. This decrease in speed is predetermined and may be carried out by any suitable driving means such as cone pulleys.

The bobbin 6 runs at a lower peripheral speed. at all times than the peripheral speed of the godet 4 whereby a reduced tension is efiected on the yarn between the bobbin and the godet wheel, thereby allowing a certain amount of contraction in the yarn at this stage.

The rotary speed of the bobbin is gradually decreased to compensate for the increase in diameter of the yarn as it builds up on the bobbin. This results in a,constant peripheral speed of the bobbin. v

Owing to the decrease in the peripheral speed of the godet wheel 4 and the constant peripheral speed of the bobbin 6, the tension between the godet wheel and the bobbin is gradually increased as the diameter on the bobbin increases thereby maintaining less contraction of the yarn progressively from the inside to the outside.

The process, therefore, in its final analysis provides for a constant stretching of the yarn and a constant decrease in contraction of the yarn. The result of processing the yarn in such a manner is that as the yarn is wound on the bobbin it has an ever increasing elongation, so that when the yarn has been driedon'the bobbin, owing to the contraction, an equal tension exists throughout the yarn'package which will, therefore, permit uniform dyeing throughout, as the so dye rate decreases in direct proportion to the increase of elongation of the filaments.

Whereas the godet wheels 3 and '4 have been described as having different peripheral speeds and constantly decreasing rates of speed, thereby producing a substantially constant stretch, they may where desirable have different perlph eral' speeds and different decreasing rates in speed, wherein a variable stretch will take place 5 between these .points, or one of the wheels may be maintained at a constant speed thereby also effecting a variable stretch. If a variable stretch is eifected then a substantially constant contraction isdesired and this can be obtained by establishing approximately the same peripheral speed between the godet wheel 4 and the bobbin 6. The results obtained by the practicing of either of the processes referred to are generally the same; that is a yarn is formed with increased elongation from the inside to the outside of the bobbin;

In the modification shown in Figures 3 and 4, a thread guide I may be substituted for the first godet wheel 3. In the use of this modified form of apparatus the stretching, action takes place between the thread guide I and the godet wheel 8. The speed of the godet wheel 8 is gradually decreased during the operation. At the same time the bobbin 9 is operated with a substantially constant peripheral speed. However, under practical conditions it is customary to increase the peripheral speed of the bobbin slightly during the formation of a complete package. Now, between the peripheral speed of the godet wheel 8 and the bobbin 9 several relations may exist; for instance, the peripheral speed of the bobbin may be less than the speed of the godet wheel during the complete formation of the yarn package, or the peripheral speed of the bobbin may be less during the beginning of the pack certain elongation given to the freshly spun yarn package.

Whereas the apparatus and process has been described as applied to the drawing, various other modifications and changes may be made to fall within the scope of the invention.

Having thus described my invention, what I claim is:

1. The process of producing artificial silk thread and the like of substantially uniform denier and having improved dyeing properties by gradually increasing the'elongation oi the thread as it is formed into a package which comprises the steps of extruding a cellulosic solution to form a thread, conducting the thread as formed to a bobbin and giving the thread different linear speeds at pre-determined spaced points in its path of travel while directly propelling the same at one or morepoints in advance of the bobbin to effect a stretching of the thread, and changing the difference in the linear speeds of the thread at the said spaced points by gradually changing the speed of propulsion at the one or more propulsion points, ,whereby objectionable characteristics resulting from contraction'are avoided.

2. The process of producing artificial silk thread and the like of substantially uniform denier, and having improved dyeing properties by gradually increasing the elongation of the thread which comprises extruding a cellulosic solution to form a thread, giving the thread different linear speeds at predetermined spaced points in its path of travel by directly propelling the samein -advance of'a bobbin so asto stretch the thread, and during the formation of a complete package, changing the difference in the linear speeds of'the thread at the said spaced 3. The process of producing artificial silk thread and the like of substantially uniform denier and having improved dyeing properties which comprises extruding a cellulosic solution to form a thread, giving the thread difierent linear speedsat pre-determined spaced points in its path of travel by directly propelling the same in advance of a bobbin so as to stretch the thread, gradually increasing the diiference in the linear speeds of the thread at the said spaced points by changing the speed at the point of propulsion, winding the, thread upon the bobbin at a reduced tension thereby permitting contraction of the thread beyond the spaced points, and reducing the amount of contraction during the winding of the thread upon the bobbin by gradually increasing the winding tension, whereby objectionable characteristics resulting from contraction are avoided.

4. The process of producing artificial silk thread and the like of substantially uniform denier and having improved dyeing properties which comprises extruding a cellulosic solution to form a thread, giving the thread di'ilerent linear speeds at pre-determined spaced points in its path of travel by passing the same around a godet at several spaced points in advance of a bobbin so that the linear speeds of the thread at the spaced points are substantially equal to the peripheral speeds of the respective godets which directly propel the same so as to stretch the thread, gradually reducing the linear speed oi successive portions of the thread as it passes between thespaced points by reducing the peripheral speeds of the godets while constantly stretching the succeeding portions of the thread, and forming a package by winding the thread onto the bobbin while the thread is maintained under a tension which varies in accordance with the tension on the thread between the said spaced points in such manner as to, give a gradual elongation of the thread as the package is being formed therefrom whereby objectionable characteristics resulting from contraction in the package are avoided.

5. The process of producing artificial silk thread and the like of substantially uniform denier and having improved dyeing properties which comprises extruding a cellulosic solution to form a thread, giving the thread diflerent linear speeds at pre-determined spaced points in its path of travel in advance of a bobbin by passing the same around a godet at each of the spaced points so that the linear speeds of the thread at the spaced points is substantially equal to the peripheral speeds of the respective godets and which directly propel the same so as to stretch the thread, gradually decreasing the rate of withdrawal of the thread as it is formed by decreasing the peripheral-speed of the godet at the predetermined poin't'flrst by thethread and operatingjhe godet at the otherpre-determined like which-comprises spinning a cellulosic solution to'form-afthread, drawing the thread from 2,078,801 point at such peripheral speed as to subject succeeding portions of the thread .to substantially constantly changing stretch, and winding the by objectionable characteristics resulting from contraction are avoided.

- 6. In the manufacture of artificial silk, a process .for i preparing threads, filaments and the a coagulatin'g 'medium by a driven godet, passing --the thread toa1point,of collection under substaritiallyfno tension during the initial spinning operation and" thereafter increasing the tension as the spinning operation continues.

7. In the manufacture of artificial silk, a proc- 'ess for preparing threads, filaments and the like which comprises spinning a cellulosic solution to form a thread, drawing the thread from acoagulating medium by a driven godet, passing the thread to'a point of collection under substantially no tension during the initial spinning operation and thereafter increasing the tension.

between the godet and point of collection as the spinning operationcontinues. I

8. In the manufacture of artificial silk, a process for preparing threads; filaments and the like which comprises spinning a cellulosic solution to form a thread, drawing the thread from a coagulating medium by a driven godet, passing the thread to a bobbin rotating at a lower peripheral speed than the godet to permit contraction of the thread therebetween and reducing the speed of the godet during the spinning period to eifect' a decrease in contraction of the thread.

9. In the manufacture of artificial silk, a process rorfpreparing threads, filaments and the like which comprises spinning a cellulosic solution to form a thread, drawing the thread from a coagulatingmedium and passing the same around at least one godet, leading the thread to a point ofcollection and collecting thesame at a constantrate and during the spinning operation decreasing the speed of the last godet with which the godet contacts to effect a gradual increase in tension whereby objectionable shrinkage characteristics normally existing are avoided.

10. In the manufacture of artificial silk, a process for preparing threads, filaments and the eral speed of the second godet at a rate lower than the decreasing speed of the first godet during the spinning operation and collecting the thread on a bobbin at a substantially constant rate. a

11. In the manufacture of artificial silk, a process for preparing threads, filaments and the like which comprises spinning a cellulosic solution to form a thread, drawing *the thread from a coagulating medium by a driven godet, passing the thread around a second godet having a higher peripheral speed than the first godet whereby the thread is stretched, progressively increasing the stretch of the thread between the said godets by decreasing the speed of the first-mentioned godet during the spinning operation while maintaining the speed of the second godet constant and collecting the thread on a bobbin rotating at a substantially constant peripheral speed which speed is maintained thesame as the peripheral speed of the second godet;

12. The process of producing artificial silk thread and the like of substantially uniform denier and having improved dyeing properties which comprises extruding'a cellulosic solution to form a thread, giving. the thread a predetermined linear speed at one point in its path of travel. be,- tween its point of extrusion and a bobbin by passing the same around a godet and directly propelling the same thereby, winding the thread upon the bobbin at a linear speed greater than the linear speed ofthe thread at the said one point so as to stretch the same, and gradually decreasing the peripheral speed of the godet with 

